Zero thermal expansion (ZTE) materials, which maintain a constant length despite temperature variations, are highly desirable for advanced industrial applications. This review highlights recent progress in exploring ZTE behavior in Fe-based Laves phases, La–Fe–Si(Al)-based alloys, and rare-earth-based systems exhibiting the magnetocaloric effect (MCE). The abnormal lattice expansion observed in giant magnetocaloric materials, driven by magnetic interactions, provides a natural foundation for designing ZTE materials. This review offers new insights into the design and discovery of novel ZTE materials within MCE systems. Furthermore, key properties such as mechanical strength, thermal and electrical conductivity, and cycling stability are also discussed, paving the way for ZTE advancements in functional materials.

Zero thermal expansion (ZTE) materials, which maintain a constant length despite temperature variations, are highly desirable for advanced industrial applications. This chapter highlights recent progress in exploring ZTE behaviour in Fe-based Laves phases, La-Fe-Si(Al)-based alloys, rare-earth-based alloys, hexagonal MM′X alloys and Mn-based antiperovskite with a giant magnetocaloric effect. The abnormal lattice expansion observed in giant magnetocaloric materials, driven by magnetic interactions, provides a natural foundation for the design of ZTE materials. Furthermore, key properties such as the mechanical strength, thermal and electrical conductivity, and plasticity are discussed. This chapter offers new insights into the design and discovery of novel ZTE magnetic materials, paving the way for advancements in functional materials.

Zero thermal expansion (ZTE) materials with the advantage of an invariable length with varying temperatures are in high demand for modern industry but are relatively rare for metals. Fe-based Laves phases attract significant attention due to the rich and intriguing physical properties resulting from the coupling between crystal, electric, and magnetic structures. In this work, the structural, magnetic transition, thermal expansion, and magnetocaloric effect of single-phase Fe_2-xHf_0.80Nb_0.20 Laves phase alloys were investigated by means of macroscopic magnetic measurements, Mössbauer spectroscopy, and X-ray diffraction at the temperature range of 4.2-400 K. With the introduction of Fe vacancies, the ZTE coefficient of −1.2 ppm/K is smaller than that (1.7 ppm/K) of stoichiometric Fe₂Hf_0.80Nb_0.20 alloy. Meanwhile, the magnetic entropy change experiences an enhancement from 0.39 to 0.50 J/kg K at a magnetic field change of 2 T. These improved properties are attributed to the vacancy-induced coexistence of ferromagnetic and antiferromagnetic phases, as evidenced by variable-temperature X-ray diffraction and Mössbauer spectroscopy. This work unveils a promising avenue for new zero thermal expansion materials by controlling the vacancies at magnetic atom positions in Fe-based Laves phase alloys.